You may get the following error when starting Apache on a FreeBSD system:

[warn] (2)No such file or directory: Failed to enable the ‘httpready’ Accept Filter

This happens because the accf_http kernel module is not loaded. This module buffers HTTP connections and prevents the application from receiving the connected descriptor via accept until either a full HTTP/1.0 or HTTP/1.1 HEAD or GET request has been buffered by the kernel. This effectively reduces the CPU utilization to handle incoming requests by keeping active processes in preforking servers such as Apache low and reducing the size of the file descriptor set that needs to be managed by interfaces such as select, poll or kevent based servers.